1. Field of the Invention
The present invention relates to a semiconductor chip packaging technique and more particularly to a double-sided circuit board and a multi-chip package including the circuit board.
2. Description of the Related Art
Since recent trends in electronics development have been toward miniaturization and high performance, chips (integrated circuits) are more integrated. In addition, different types of chips need to be contained in a single package body, in order to achieve various semiconductor devices. In order to satisfy these pressing demands, a multi-chip packaging technique is applied.
FIG. 1 is a sectional view showing a conventional multi-chip package using a circuit board.
A conventional multi-chip package 100 is a fine-pitch ball grid array (FBGA). A first chip 120 is attached to a first surface of a circuit board 110, and a second chip 130 is attached to the first chip 120 with an adhesive tape 135. The first chip 120 and the second chip 130 are electrically connected to bonding pads 140 by bonding wires 143, 145 which are formed on the circuit board 110. The conventional FBGA multi-chip package 100 uses a chip stacking technique and a wire bonding technique.
The first and second chips 120, 130 and the bonding wires 143, 145 are protected by package body 150 of molding compound. A plurality of solder balls 160 is attached on the second surface of the circuit board 110. The solder balls 160 are connected to solder ball pads 141, which are formed on the first surface of the circuit board 110, thereby electrically connecting the multi-chip package 100 with a mother-board or other electrical devices.
In the conventional multi-chip package 100, adhesive tape 135, which is used for attaching the second chip 130 to the first chip 120, does not encroach upon the wire bonding area of the first chip 120. Therefore, the second chip 130 must be smaller than the first chip 120. Since the second chip 130 is distant from the bonding pads 140 of the circuit board 110, the bonding wire 145 must be formed in an almost straight-lined loop, so as to shorten the length of the bonding wires 145. Accordingly, it requires an additional apparatus and technique for the wire bonding process.